The invention relates to a suction head for connection to a fuel hose in a fuel tank. The suction head is comprised of a housing-shaped base member made of an injection molding material, wherein the base member has an end face opening that is closed off by means of an attached cap. The suction head comprises a connecting socket for the fuel hose wherein the connecting socket can be integrally formed on the base member or on the cap. In the base member of the suction head, a first filter element is received. The base member has cutouts in its outer wall that are covered by a second filter element.
Such suction heads with filter properties are preferably used in power tools that are carried by an operator and provided with a two-stroke engine, a four-stroke engine or a mixture-lubricated four-stroke engine as a drive motor. Due to the connection to a flexible fuel hose, the suction head is located at the lowermost part of the fuel tank and ensures in this way a position-independent fuel supply to the internal combustion engine.
In operation of the internal combustion engine, a liquid fuel/oil mixture flows through the suction head to the mixture forming device. The fuel/oil mixture first flows through the outer filter element and then through the inner filter element and the fuel hose to the mixture forming device. Dirt particles are primarily retained at the outer filter element wherein the smooth side of the outer filter element which is comprised of filter fabric favors the formation of a filter cake. When deposited dirt particles have combined to a filter cake, removal from the filter fabric by movement and vibration of the suction head is hardly possible anymore. The flow resistance of the suction head rises and the fuel conveyance rate drops so that disturbances in regard to operation of the internal combustion engine may occur. For example, in case of hand-carried power tools that have a carburetor with a solenoid valve, dirt particles may impair the function of the solenoid valve.
The invention has the object to further develop a suction head of the aforementioned kind in such a way that, while providing a high filtering action over an extended operating period, the flow resistance of the suction head does not rise undesirably.